The update opens level 46 to 50. In my case I was level 45 and lots of extra experience points so it took 5 minutes to go up from 45 to 50. Actually, every time I did something that brings experience points (land a plane, complete a mission,...), I levelled up, with interesting benefits:- 1 green- 1 more max fuel (I have now 100)- opens 1 new destination and 1 corresponding small quest- restores your fuel to 100%

The last bit is of particular interest if you time it properly, as it gives you something like up to 500 free fuel!

When you open the game the first time after upgrade, don't touch any new side mission and don't land any plane. Send all your planes to somewhere (use all your fuel), then complete 1 mission (they're all trivial, like complete terminal level 3). You have 100% fuel again. Send more planes (or bring them back), hit one mission if needed: 100% fuel again! Repeat 5 times. Quite useful for large planes.